Lightly grease an 8 inch square baking dish and set aside.
Bring water to boil in a large sauce pan.
Slowly add polenta, stirring constantly.
Reduce heat to low and cover. Cook, stirring often until polenta is tender and water has been absorbed, 5-10 minutes.
Stir in nutritional yeast, salt, garlic powder, onion powder and red pepper flakes, if using. Taste and adjust seasonings to your liking.
Pour polenta into prepared baking dish and spread in an even layer. Allow. to cool and firm, about 1 hour.
Cut polenta into 16 squares and transfer to a baking sheet. Heat broiler.
Sprinke with cheese and add tomatoes, olives, or any other garnishments.
Broil until cheese is melted, cool briefly and serve.